Pneumatic tires are conventionally of an open toroidal shape which defines a cavity which is substantially enclosed by the tire and the closure of the cavity is conventionally completed by mounting the tire on an intended rigid rim. The tire conventionally has a rubber innerliner which is co-existent with and is an exposed surface of the tire cavity. Such pneumatic tire configurations are conventional as would be understood by one having skill in such art.
Pneumatic tires usually rely upon air pressure to maintain their shape and associated performance during service conditions, although some pneumatic tires may be designed to hold their shape and provide representative performance, at least for limited times, even though they may have lost or are not able to maintain their internal air pressure for various reasons. For the purpose of the description of this invention, such tires are considered herein to be pneumatic tires even though they might be designed to run without an internal air pressure for limited periods of time.
For various applications, it may be desirable to provide a pneumatic rubber tire with a sensing device (e.g. transducer and associated microprocessor) on its inner surface which has a capability of electronically receiving power generated from an electromagnetic wave generating source outside the tire and transmitting various data relating to the tire such as, for example, its internal air pressure and temperature relative to an external transmitting and receiving device.
It may be desirable to provide such a tire with a suitable antenna as an actual part of the tire for both receiving various electromagnetic signals from an exterior source by an internal sensing device within the tire such as a transducer and for transmitting various electromagnetic signals from within the tire to an external receiving device. For the purposes of the description of this invention, such components which may include one or more of a transducer, associated dedicated integrated circuit microprocessor and other associated component(s), and particularly a transponder, which are more simply collectively referred to herein as a microprocessor.
In practice, such antenna may be provided as at least one electrically conductive element (e.g. a metallic wire) extending substantially throughout the length of the rubber strip, particularly where the pre-cured rubber strip is in a form of an annular rubber strip. The antenna may be connected, for example, to the microprocessor either physically or inductively.
Such an annular rubber strip will contain at least one electrically conductive element basically extending substantially or entirely throughout its length (e.g. one or more electrically conductive metal wires) for its purpose and have suitable elastomeric properties for compatibility with the inner rubber surface of the tire.
For this invention, it is envisioned that such annular rubber strip, generally in a form of a ring, is provided as being bonded to an inner surface of the toroidal tire cavity via an RTV (room temperature vulcanizable in the presence of moisture such as example atmospheric humidity) hydroxyl terminated (namely silanol terminated) organosiloxane composition.
Representative of such RTV compositions for use in this invention are those which are comprised of a silanol terminated organopolysiloxane and a silane based crosslinking agent which contains a silane group such as —Si—Rx, where x is a value of from one to and including three, capable of crosslinking a silanol terminated organopolysiloxane. Representative of such silane based crosslinking agents are those having at least one silane group capable of crosslinking a silanol terminated RTV organopolysiloxane where R may be selected from at least one of oxime, acetoxy, methoxy, ethoxy, amine, oximino and enoxy moieties and their mixtures. Thus, it is contemplated that such silane group may be, for example, an oximesilane, acetoxysilane, methoxysilane, aminesilane, oximinosilane and/or enoxysilane, so long as it has a capability of crosslinking the RTV organopolysiloxane. Such silane based crosslinking agents for crosslinking silanol terminated RTV organopolysiloxane are well known to those having skill in such art. For one aspect of the practice of this invention an oximinosilane is preferred. Examples of various oximinosilane and oxime related RTV crosslinking agents are, for example, illustrated in U.S. Pat. Nos. 6,200,411, 4,918,209, 4,400,527, 4,380,660 4,735,979, 3,189,576, 4,323,489 and 4,720,530. An example of use of an acetoxy based crosslinking agent may be found, for example, in U.S. Pat. Nos. 3,382,205 and 3,035,016. Hydroxyl terminated (namely silanol terminated) organopolysiloxanes for use in RTV compositions for the purposes of this invention may be hydroxyl terminated organopolysiloxane, dihydroxyl terminated organopolysiloxane, hydroxyl terminated in diorganopolysiloxane and dihydroxyl terminated diorganopolysiloxane. The hydroxyl groups are envisioned as being silanol groups. Representative examples of hydroxyl terminated organopolysiloxanes for use in an RTV composition are illustrated, for example, in one or more of the above U.S. patents as well as U.S. Pat. Nos. 6,013,754 and 6,437,039.
For the description of this invention, the term “phr” refers to “parts by weight of a designated ingredient in a rubber composition per 100 parts by weight of rubber”.
The terms “rubber” and “elastomer” are considered herein to be interchangeable unless otherwise indicated.
The terms “rubber compound” and “rubber composition”, or “elastomer composition”, where used, are considered herein to be interchangeable unless otherwise indicated. The terms “vulcanized” and “cured” are used interchangeably under otherwise indicated.
In the description of this invention, various RTV polysiloxane compositions are described which are comprised of a silanol terminated polysiloxane and crosslinking agent which may be in a form of a one part RTV adhesive which contains both the silanol terminated polysiloxane and the crosslinking agent or may be a two part adhesive in which the user mixes a first part comprised of the silanol terminated polysiloxane with a second part comprised of the crosslinking agent prior to application. Such use of one part and two part RTV adhesives is well known to those having skill in such art.